Question

Which of the following is not an ambidentate ligand?

• A. C₂O₄²⁻
• B. SCN⁻
• C. NO₂⁻
• D. CN⁻

Answer 1

The Correct Option is A

To determine which of the given ligands is not an ambidentate ligand, it is essential to understand what ambidentate ligands are. Ambidentate ligands are those ligands that can attach to a central metal atom or ion through two different atoms. Here's how to analyze each option:

\(C_2O_4^{2-}\) (oxalate ion): 

This ligand is a bidentate ligand, not an ambidentate ligand. It can coordinate with the metal ion through two oxygen atoms, forming a chelate. It does not switch between different donor atoms, which disqualifies it from being ambidentate.

\(SCN^-\) (thiocyanate ion):

This is an ambidentate ligand because it can attach to the central atom either through the sulfur atom (S) forming one link, or through the nitrogen atom (N) forming another possible link. Hence, it has two potential donor atoms.

\(NO_2^−\) (nitrite ion):

This ion is also ambidentate as it can bind through either the nitrogen atom or the oxygen atom.

\(CN^-\) (cyanide ion):

Cyanide is not ambidentate. It generally binds through the carbon atom of the CN group, hence it does not provide two different atoms for attachment like ambidentate ligands do.

Conclusion: The ligand that is not ambidentate among the given options is \(C_2O_4^{2-}\), as it binds through both oxygen atoms and does not provide different donor atoms for linkage.